1. Field of the Invention
This invention relates to a flexure used in a disk drive for an information processing apparatus, such as a personal computer.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The hard disk drive comprises a magnetic disk rotatable about a spindle, carriage turnable about a pivot, etc. A disk drive suspension is disposed on an arm of the carriage.
The disk drive suspension comprises a baseplate and load beam. A flexure is located on the load beam. A slider is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for accessing data, that is, for reading or writing data. The suspension, flexure, etc., constitute a head gimbal assembly.
The flexure is any of various available types used depending on the required specifications. A flexure with conductors is a known example. The flexure with conductors comprises a metal base formed of a thin stainless-steel plate, resin layer formed of an electrically insulating resin, such as polyimide, a plurality of conductors of copper, etc. The resin layer is formed on the metal base. The conductors are formed on the resin layer. One end of each conductor is connected to an amplifier or the like of the disk drive. The other end of each conductor is connected to an element (e.g., MR element) of the slider.
The impedance of a conductive circuit portion of the flexure is expected to be reduced in order to match the amplifier and the element of the slider and reduce energy consumption. The inductance is also expected to be reduced. For higher data transfer, moreover, such a property (low-attenuation property) is required that attenuation is low even in a high-frequency band.
A flexure with conductors comprising multi-trace transmission lines can effectively meet these requirements. A circuit provided with the multi-trace transmission lines is also called an interleave circuit. A flexure with an interleave circuit is disclosed in U.S. Pat. No. 5,717,547. The flexure of this type is suitable for high-speed data transfer because of its low attenuation in the high-frequency.
FIG. 16 shows an example of a conventional interleave circuit. This interleave circuit comprises first to fourth interleaved conductors 201 to 204. The first and second interleaved conductors 201 and 202 diverge from a first conductor member 211. The third and fourth interleaved conductors 203 and 204 diverge from a second conductor member 212.
Thus, the second and fourth interleaved conductors 202 and 204 three-dimensionally cross at an intersection 220. Further, the second and third interleaved conductors 202 and 203 three-dimensionally cross at an intersection 221. Connecting wires 230 and 231 with electrically insulating coatings are used to prevent short-circuiting of the intersections 220 and 221.
If the connecting wires 230 and 231 are used for the intersections 220 and 221, as in the prior art example shown in FIG. 16, they inevitably project vertically relative to the interleave circuit, so that the thickness of the interleave circuit cannot be reduced favorably. Since the connecting wires 230 and 231 are required in addition to the interleaved conductors 201 to 204, moreover, there is also a problem of an increase in the number of components.
The inventor hereof carried out a test in which high-frequency data was transferred to the interleave circuit shown in FIG. 16. In this test, the respective phases of the waveforms of currents that flow through respective midpoints m1 and m2 of the interleaved conductors 201 and 202 were measured. Consequently, it was found that a substantial phase difference was produced between current waveforms W1 and W2, as shown in FIG. 17, and variation in properties was caused by electrical interaction or the like. It was also found that, depending on the mounted state of the connecting wires 230 and 231, high-frequency attenuation, in particular, may be so high that high-speed data transfer is hindered.